Transcriptome profiling analysis reveals involvement of SAM cycle and methionine pathway in low potassium tolerance in barley

Abstract Available potassium in most agricultural soils is not sufficient for requirement of crop growth and development, and K deficiency has become a bottleneck of crop production worldwide. Development of low-K tolerant crop cultivars is an effective approach for relieving K deficiency. In the previous studies we identified some Tibetan annual wild barley accessions with higher low-K tolerance than cultivated barley. In this study, Illumina RNA-Sequencing was performed on the four-leaves seedlings of a Tibetan wild barley accession (XZ153, low-K tolerance) and a barley cultivar (ZD9, low-K sensitivity) to compare their transcriptome profiles in response to low-K stress. A total of 7263 differentially expressed genes (DEGs) were detected in the topmost 2 and 3 leaves (YL2, YL3) of the two genotypes under low-K stress, with XZ153 and YL2 having larger change than ZD9 and YL3, respectively, in terms of DEGs number and expression level. Meanwhile, 1395 low-K tolerance associated DEGs were mapped to metabolic process, translation, RNA methylation and responses to abscisic acid and other gene ontology (GO). The responses of XZ153 and ZD9 to low-K stress differed dramatically at the transcriptional level. The higher low-K tolerance in XZ153 is attributed to its more K uptake and accumulation in the topmost 2 leaf (YL2). The S-Adenosyl- l -methionine (SAM) cycle and methionine pathway involving in ethylene biosynthesis may account for the genotypic difference in low-K tolerance.